After Dismal Primary Day, Santorum Retreats To Pa.

DAVID WELNA, BYLINE: I'm David Welna in Mars, Pennsylvania. If there was bad news for Rick Santorum last night from the primary results, his supporters who flocked to a suburban hotel ballroom didn't want to know about it.

(SOUNDBITE OF RALLY)

WELNA: Santorum told them only half the game has been played so far, and that it was good to be back in this stronghold of conservative voters, just 20 miles from where he grew up.

RICK SANTORUM: This is why we came here. This is why we wanted to come back to southwestern Pennsylvania to kick off the second half.

WELNA: And Santorum took a shot at Mitt Romney, insisting that only a true conservative can beat Barack Obama, a challenger with values forged in steel rather than with an Etch-A-Sketch.

SANTORUM: Time and time again, the Republican establishment and aristocracy have shoved down the throats of the Republican Party and people across this country moderate Republicans because of course we have to win by getting people in the middle. There's one person who understood we don't win by moving to the middle. We win by getting people in the middle to move to us and move this country forward.

(SOUNDBITE OF CHEERING)

WELNA: Santorum predicted he'll win the April 24 primary in Pennsylvania, where he has a small edge over Romney in recent polls.

SANTORUM: And so I ask you over the next three weeks - this isn't halftime. No marching bands. We're hitting the field. The clock starts tonight.

WELNA: Barb Johnson, of nearby Baldwin, Pennsylvania, wants to see Santorum take his fight all the way to the convention in Tampa.

BARB JOHNSON: He doesn't have the money that Romney does, but he's - but he has a message that we like. And I think it resonates with a lot of people.

WELNA: But some supporters like Warrendale realtor Pierre Cory said they saw Pennsylvania as do or die for the native son.

PIERRE CORY: If he doesn't make it here, he needs to bow out. Do what he needs to do.

WELNA: But that question's been pushed to the future. And for now, at least, the Santorum insurgency continues.